Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree of Master of Science in the School of Informatics Indiana Univeristy / A QSAR using Comparative Molecular Field Analysis (CoMFA) is developed for a set of 23 catalysts containing bis-oxazoline or phosphino-oxazoline ligands that are known to induce asymmetry during the Diels-Alder reaction of N-2-alkenoyl-1, 3-oxazolidine-2-one with cyclopentadiene. It is shown that extemely high q2 statistics can be derived using standard modeling protocols when internal validation alone is done as well as when an external test set is used. From these models it is shown that approximately 70% of the variance in the observed enantiomeric excess can be attributed to the steric field and the remainder of the variance to the electrostatic field. Suggestions about how to improve the performance of inefficient catalysts are given the thesis.

Asymmetric catalysis is vitally important for modern organic chemistry. However, many chiral catalysts are readily available only in a single absolute configuration. This often prevents practical access to both enantiomers of a product. To address this shortcoming, we propose a novel type of accessible ligands based on the structure of trans-5,6-disubstituted-5,6-dihydro-1,10-phenanthroline. Conformers of this molecule have opposite twist in the bipyridine fragment (opposite helicity or axial chirality). Thus, a relative stabilization of one or the other conformer of the same chiral precursor could potentially give access to two ligands with opposite axial chirality and hence to two catalysts with opposite enantioselectivity. We proposed structural modifications of substituents attached to 5,6-dihydro-1,10- phenanthroline as a convenient and reliable approach for stabilization of one or another conformer. To validate this strategy, multiple oxygen- and sulfur-substituted ligands were synthesized and fully characterized. In particular, their conformational behavior was studied by 1H NMR. Some ligands and their metal complexes were designed and proved to be conformationally (axially) constrained. Chiral resolution of these ligands through separation of their diastereomeric derivatives was accomplished, resulting in material of high optical purity. The absolute configuration of chiral elements (centers and axis) were established by 1H NMR, CD and X-ray analysis. Metal complexes with a range of novel chiral 5,6-dihydro-1,10-phenanthrolines were assessed as chiral catalysts for the asymmetric alkylation of aldehydes, Henry reaction and allylic substitution. Moderate to high activities were achieved in all catalytic transformations while low to moderate degree of enantioselectivity was observed. The results of asymmetric catalysis confirmed the crucial role of the twist in the ligand’s bipyridine moiety (of its sign and magnitude) in the induction of stereoselectivity. Exploring an undesired aromatization of products in cleavage of 5,6-epoxy-5,6- dihydro-1,10-phenanthroline with various thiols in presence of base, we developed a new simple procedure and synthesized a broad library of novel valuable ligands: 5-aryl(alkyl)sulfanyl-1,10-phenanthrolines and bis(1,10-phenanthrolines). Other functional groups attached to the thiol moiety allow using these products as building blocks for versatile ligands and in functionalization of surfaces. Besides, the new sulfur- substituted derivatives were found to be potent modulators of fungal glycosidases.

In this study new twelve phosphorus based chiral ligands were synthesized and characterized. Then the catalytic activity of these chiral ligands was tested with Cu(II) and Ag(I) salts in asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides. This method provides the synthesis of different pyrrolidine derivatives with up to four stereogenic centers. Pyrrolidine derivatives are found in the structure of many biologically active natural compounds and drugs. Therefore the asymmetric synthesis of these compounds is highly important and many groups are involved in this area. As the precursor of the azomethine ylides, N-benzyliden-glycinmethylester, N-(4-methoxy benzyliden)-glycinmethylester, N-(naphthalene-1-ylmethylene)-amino-acetic acid methyl ester, and N-(naphthalen-2-ylmethylene)-amino-acetic acid methyl ester were synthesized and used. As the dipolarophiles, methyl acrylate, dimethyl maleate and N-methyl maleimide were used. Using these imines and dipolarophiles with 6 mol % of one of the P-FAM chiral ligands in the presence of Ag(I) salt, pyrrolidine derivatives were synthesized in up to 95% yield and 89% enantioselectivity. Additionally, chiral ligand was recovered in more than 80% yield and reused without losing its activity.

Chiral bisphosphinites are well-documented alternatives for chiral bisphosphines as ligands that can be exploited in various asymmpetric syntheses. Particularly, vicinal biarylphophinite ligands give a seven membered chelate ring similar to the successful DIOP on coordination to the metal. RajanBabu and coworkers have described asymmetric bisphosphinites obtained by functionalization of sugars and have shown their utility in enantioselective hydrogenation, hydrovinylation and hydrocynation reactions. Despite the interesting reactions demonstrated by bisphosphinites, not much attention has been paid to their synthesis and catalysis. This is probably due to the known moisture and oxygen sensitivity that makes their use limited. In the present thesis, a series of C1 an C2 symmetric bisphosphinite complexes of Pd(II) and Pt(II) have been synthesized directly from various naturally occurring chiral alcohols using a modified template method. A number of asymmetric catalytic reactions have been developed such as allylation of imines, allylation of aldehydes, allylic allylation, allylic alkylation, hydrosilylation of alkenes and regioselective allylation of oxiranes. Allylation of imines was carried out in essentially neutral conditions using Pd(II) catalysts and water was shown to accelerate the reaction. Interestingly acetic acid was required as a promoter in asymmetric allylation of cinnamaldehyde in the Pt(II) catalyzed reaction whereas water was a deterrent. Hydrosilylation reaction was carried out in solvent free conditions with high turnover numbers (.1000). Ascorbic acid based complexes produced the highest enantioselectivity for the asymmetric allylic alkylation reaction (97 % ee) and hydrosilylation of styrene (98% ee). These enantioselectivity results are the best obtained using ligands directly prepared from natural products.

La catalyse organométallique est l’un des outils les plus puissants de la synthèse chimique, car elle permet de réaliser des transformations sélectives et spécifiques selon le catalyseur employé. Dans ce contexte, les sels et complexes d’or ont émergé il y a une quinzaine d’années et se sont révélés très utiles et attractifs pour la synthèse organique, faisant preuve de propriétés particulières de type acide de Lewis à la fois π (alcyno- alcènophilie) et σ (oxo- azaphile). L’objectif initial de cette thèse a été d'approfondir l’étude de la réactivité de l’or au travers la mise au point de nouvelles réactions catalysées par l’or(I/III). Si la majorité des réactions développées en catalyse à l’or concerne des processus de type π, nous avons dans un premier temps, souhaité évaluer son potentiel dans une réaction qui repose sur une activation purement σ, la cyclisation de Nazarov. Cette réaction a ensuite été étendue à un processus de type cascade, combinant activations π et σ. De plus, la formation d’un sous-produit inattendu au cours de cette étude a orienté nos recherches vers un nouveau processus catalytique, le réarrangement de γ–acyloxy alcynylcétones en furanes. Par la suite, nous nous sommes aussi intéressés au potentiel de l’or dans les réactions asymétriques, ce qui a conduit au développement d’un nouveau type de complexes d’or chiraux basés sur des ligands de type NHC-oxazoline. Enfin, nous nous sommes proposés d’utiliser la spectroscopie RMN J-résolue hétéronucléaire (une méthode simple mais peu exploitée), pour répondre à des problèmes d’attribution structurale. / Organometallic catalysis is one of the most powerful tools in chemical synthesis, because, depending on the catalyst, it allows for selective and specific transformations. Thus, the reactivity of gold salts and complexes was revamped around fifteen years ago. Nowadays, they are considered as powerful and very attractive for organic synthesis, showing both π (alcyno- alcènophilie) and σ (oxo- azaphile) Lewis acid properties.The first objective of this thesis was to study the reactivity of gold catalysts by the development of new reactions catalyzed by gold(I/III). If most of the developed reactions in gold catalysis is related to π activation, we proved its potential in a reaction dealing with σ activation, the Nazarov cyclization. This reaction was then extended to a cascade process, combining both π and σ Lewis acidities. Moreover, the obtainment of an unexpected by-product during the study directed our research towards a new gold catalytic reaction, the formation of furans from γ-acyloxyalkynyl ketones. Subsequently, we were also interested in the potential of gold in asymmetric reactions, which led to the development of new chiral gold complexs, based on NHC-oxazoline type ligands. Finally, we proposed to use the heteronuclear J-resolved NMR spectroscopy (a simple but scarce method), to answer some structural assignment problems.